Bule exposure mechanism for camera shutters



Sept. 7; 1948. c. c; FUERST 3 5 BULB EXPOSURE MECHANISM FOR CAMERA SHUTTERS u a May 25, 1947 2 Sheets-Sheet 1 CARL C.FUERST 4. INVENTOR 4 M 70 71 7 ifiw fiw 73 72 ATTORNEYS C. C. F UERST Sept. 7, '"1948.

4 puma EXPOSURE ME ANISM FOR CAMERA SHUTTERS Filed May 23, 1947.

2 Sheets-Sheet 2 'I/Il'I/IIIIIIIIIIIIII.

'II IIIIIIIIIIIIIIII IIIIIIIII f H m 7 ATTORNEYS IN VEN TOR Patented Sept. 7, 1948 BULB EXPOSURE MECHANISM FOR CAMERA SHUTTERS Carl C. Fuerst, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application May 23, 1947, Serial No. 750,009

This invention relates to camera shutters and more particularly to the mechanism for producing prolonged exposures with such shutters, usually known as "bulb exposures. One object of my invention is to provide a mechanism by which prolonged bulb exposures can be readily obtained with a shutter blade and cover-blind type of shutter. Another object of my invention is to provide a shutter having shutter blades which open and close during the tensioning movement, these blades operating in timed relation to cover blinds which remain closed until the shutter is tensioned, after which the cover blinds may be opened to permit an exposure to be made and to provide a suitable mechanism for operating the cover blinds and shutter blades in proper sequence for a bulb exposure. Other objects will appear from the following description, the novel features being particularly pointed out in the claims at the end thereof. In most shutters having a single set of shutter blades which only open and close when an exposure is to be made, it is customary to produce a bulb exposure by providing some form of stop which will hold the blades open as long as the shutter trigger is depressed, and permit the blades to close after the bulb exposure has been completed. However, when shutters are of the type in which the shutter blades both open and close in setting and in which cover blinds must be used to prevent exposure in setting, it is a somewhat more difiicult problem to provide for prolonged exposures and to move the cover blinds out of their operative position so that the desired type of exposure can be made. This bulb exposure mechanism is particularly adapted for use in a shutter of the type fully described in my copending application Ser. No. 749,482, for Automatic high speed symmetrical blade and cover blind shutter, filed May 21, 1947.

Coming now to the drawings wherein like reference characters denote like parts throughout:

Fig. 1 is a top plan View of a portion of a shutter mechanism showing a bulb exposure device constructed in accordance with and illustrating a preferred embodiment of my invention. In this figure, the shutter cover plate and cam plate have been removed to expose the blade and cover-blind operating mechanism;

Fig. 2 is a fragmentary view of a portion of the shutter cover plate and the exposure-setting cam portions of the cover plate bein broken away to expose the cam ring;

Fig. 3 is an enlarged fragmentary sectional view taken on line 33 of Fig. 1;

Fig. 4 is a view'similarto Fig. 1, but with the 6 Claims. (01. 95-60) 2 shutter blades and cover blinds fully opened for bulb exposures;

Fig. 5 is an enlarged fragmentary taken on line 55 of Fig. 4; and

Fig. 6 is a view of the cover blinds removed from the shutter casing and shown in their inoperative, or fully-opened position.. I

My preferred bulb type of exposure-making mechanism may be built into a shutter of the automatic type as shown herein, this shutter being of the type in which symmetrically-shaped shutter blades open and close as the blade-operating spring is tensioned, during which time cover blinds cover the exposure opening. This is accomplished by depressing a trigger and during the last part of the trigger movement and, after the shutter blades have closed, the cover blinds are opened and then the shutter is tripped, permitting the shutter blades to open and close, moving in a reverse direction to make an exposure.

As indicated in the drawings, the shutter casing I may be of the usual type having an upstanding flange 2 around the periphery and including an exposure opening 3. This exposure opening, as indicated in Figs. 3 and 5 may contain at 4 a diaphragm of a known type for varying the aperture of the exposure opening. Such ,diaphragms are well known and do not form a part of the present invention. Over the top of the diaphragm blades 4, there is a ring 5 which spaces the cover blinds 6 from the diaphragm blades and over the top of the cover blinds 6 there is a ring "I forming one of the mounts for the shutter'blades 8. The shutter blades 8 may be mounted upon studs 9 carried by a mechanism plate ID, as best shown in Fig. 5. A blade ring I I is provided with slots l 3 for receiv-, ing studs l2 extending upwardly from the shutter blades. With reference to Fig. 1, when the blade ring II is moved in a clockwise direction, the blades will also move in such a direction about their pivotal points 9, first opening and then closing the exposure aperture 3.

This setting movement is obtained in the following manner. The blade ring H is provided with an upstanding beveled pin M. This pin lies in the path of an arm [5 which is a separate part from the trigger it but which, nevertheless, turns with it because of a pin ll carried by the trigger extending up through a slot I8 in the arm l5 which, like the trigger I6, is pivotally mounted upon a stud l9 carried by the mechanism plate sectional view It. A spring 20 exerts an axial thrust downwardly upon the arm 15, this spring also being mounted to turn upon the stud l9 and havinga slot 2| through which the pin II, passes so that the spring will turn with the arm.

When the trigger I5 is moved in the direction shown by the arrow in Fig. 1, the cam edge 22 of arm I5 moves the pin I4 in a clockwise direction. This movement tensions a driving spring 23 attached to -the blade-ringl I by'meansof-a-pin t4 and attached to the mechanismiplatelil by means of a spring 25. This movement of the blade ring I I continues with the trigger movement until the end of the cam 22 is reached at which time a second cam 26 on the end of lever'l'5 "takes over. The shape of this cam is such that the blade ring pin the end of the setting movement with the spring 23 fully tensioned until slight further and final movement Of the trigger causes the cam 2b to slip off the pin I4, permitting'the'sp'ring tomove the blade ring I I in a counterclockwise direction, rocking the blades counterclockwise to open and close the exposure aperture. As the blade ring pin I4 moves through its slot 21 in the mechanism plate II), it engages the arcuate cam "28 on the lever I5 and prevents the lever from turning'and, consequently, the trigger normal position-of rest in Fig. 1.

It is, of course, necessary to momentarily hold open the cover blind 6 shown'in Fig. 6 during the exposure taking movement of the blades. This is accomplished as follows. The blinds 6 are pivoted upon studs 30 and 3I and one of these blinds has a pin 32 extending upwardly through a slot 33 in the other blind, so that both blinds are moved together in opposite directions and to equal extent as the pin 32 is moved. A spring 34 normally holds these blinds inan operative position by .pressing on the pin '32, this spring encircling the trigger stud I9 and being shown under tension in Fig. 4. I

For ordinary exposures, the pin 32 is engaged and moved by the trigger arm 35 being moved to its completely-open position just in advance of thes'lip-off between the cam 26 and theblade ring pin I4. This is accomplished for normal exposures, as fully described in my copendi'ng' application and need'not be additionally referred to here.

There is, however, a second means for operating the cover blind 6 and this is used for making "bulb" exposures.

In Fig. 2, a portion of the shutter cover plate 40 is shown, this cover plate being held by the front shutter extension M which is threaded at 42 to receive a front lens cell. It also rests in a rabbet 43 in the 'cam plate 44 which is mounted to turn on the periphery 45 of the flange 2' and which is preferably provided with a roughened or knurled edge 46 for turning the cam "plate between the cover 40 which remains stationary and the shutter flange 2. As best shown in Fig. 2, there is a vpointer 41 on the adjusting ring and the cover plate 40 bears a series of, graduations 49 indicating automatic shutter speeds and an indication 50, here shown as B, to indicate when the shutter mechanism is set for bulb exposures. The cam 5i may adjust an upstanding pin 52 of a bell-crank lever 53 pivoted at 54 to the shutter mechanism plate and having an arm 55 which may be moved more or less into the path of blade ring pin 24 to retard its movement through the gear train shown broadly as 56. This construction is shoWn in my copending application.

, The cam ring 44 is also responsible for "bulb ex-posures and, to that end, it is provided with, a

I4 may be held substantially stationary at 'from returning to its blades 8 to a fully-opened position. This position is shown in Fig. 4. As soon as pressure on ".tlre'trig'ger 'I'Iiis released, it will return under the impulse of its spring 60 to its normal rest posit'ion showninFig. 1. It is noted that the flange 5B"'of the'trigge'r lies in the path of a cable rehearse-plunger P which may operate the shutter in lieu ofthe shutter trigger I6 by passing through a ferrule'fil in the shutter flange 2.

The-cam 44 accomplishes the additional function of moving the cover blinds 6 to their inoperative position of Fig. 6 and-out of the pathof the trigger. This is accomplished by the cam slot 63 shown-in Fig. 2, the slot ending in a narrow notch 64, so positioned that when seton B the cover-blind operating pin -32 will ride up'and be confined in the narrow slot 64, thereby moving the'cover blind to the Fig. 6 position. When the knurled ring 46 is moved'clockwise from the Fig. 2 position, the pin 32 may return "the cover blinds 6 to their operative position by moving down the ramp '63 of the cam slot, thus positioning the cover blinds for their normal function "for in stantaneous exposures described above.

The rear wall I0 of the shutter casing is provided with a threaded tubular extension I I, the

inner thread I2 being normally used to receive a rear lens element and the outerthrea'd T3 being normally used to hold the shutter on a lens boar'd asby the use of a threaded collar.

It will be seen from the above description that when bulbexposures are made, the shutter triggeronly has one set of blades to move, that is, the shutter blades, and these are only moved to half their usual extent, opening the exposure aperture 3. Since the spring 23 is placed under tension during this movement, the release of this trigger causes this spring to immediately return the blades to their operative aperture-covering position shown in Fig. 1. The cover blinds are-of course, moved to their inoperative position in setting the knurled member 46 to its Fig. 2 position,

since, by turning the cam ring, the pin 32 is slid against the pressure of spring 34 to its outermost position as it moves up the-ramp63 into the notch 64 defining the inoperative positionof the shutter leaves. For instantaneous exposures, the trigger moves both the shutter leaves and the cover blinds in timed relation for bulb exposures; 'for bulb exposures the trigger moves only the shutter blades to an open position and then permits them to move to a closed position under the impulse of the blade ring spring 23. This construction provides a simple means for producing exposures of any desired duration, which bulb exposures are made by opening the shutter blades 2 through depressing the trigger through approximately half of its usual stroke and then by re leasing the trigger, permitting the blades to close.

I claim: 1. In a camera shutter of the type including an apertured casing, 'a plurality of shutter blades mounted in the casing, cover blindpivotal-1y mounted in the casing, the combination with said shutter blades and cover blind, of mechanism for operating the shutter blades and cover blind in timed relation for normal exposures, said mechanism including a trigger, a setting device for setting the shutter for diiferent exposures including bulb and means carried by the setting device for moving the cover blind from an operative to an inoperative position for making bulb" exposures whereby actuation of the trigger may make a bulb exposure with the shutter leaves alone.

2. In a camera shutter of the type including an apertured casing, a plurality of shutter blades for making an exposure and cover blinds for normally covering the exposure aperture, the combination with said shutter blades and cover blinds, of mechanism for normally operating the shutter blades in timed relation to the cover blinds for automatic exposures, a setting dial to determine the character of exposures including bulb exposures and means operable thereby for moving the cover blinds open and limiting the mechanism movement for operating the shutter blades to an extent to hold the shutter blades open when said setting dial is moved to a bulb position, and a trigger, forming a part of the mechanism for manually operating the mechanism for releasing the shutter blades for making an exposure when said dial is set for bulb" exposures.

3. In a camera shutter of the type including an apertured casing, a plurality of symmetricallyshaped, pivotally-mounted blades in the casing adapted to move to open and close the aperture,

the combination with said blades, of a blade ring operably connected with the blades for moving the blades, a pin on the blade ring, a spring normally moving the blade ring in one direction, a trigger for setting and releasing the blade ring spring, a pair of cover blinds pivotally mounted in the casing and movable to open and close the shutter aperture, means for opening and closing the cover blinds by the trigger in timed relation to the shutter blades and an exposure dial on the shutter movable to indicate difierent types of exposures including bulb, said dial when moved to bulb setting including means for opening the cover blinds independently of the trigger, said dial also including means movable into the path of the trigger when set for bulb for limiting the trigger movement whereby pressure on the trigger may open the shutter blades and release of the trigger may cause the shutter blades to close under the influence of the blade ring spring.

4. A bulb exposure shutter mechanism for camera shutters including an apertured shutter casing, cover blinds pivotally mounted in the casing and normally held in an operative position covering the aperture by a spring, shutter blades pivotally mounted in the casing, mechanism in the shutter for moving the blades in one full stroke in one direction to open and close the apertured casing to make an exposure, said mechanism including a trigger and means on the trigger for also moving the cover blinds, a movably-mounted bulb exposure control carried by the shutter and means carried thereby for actuating the cover blinds to an inoperative position in which they do not cover the aperture in the casing by moving the bulb control to a bulbindicating position, said bulb control also positioning a stop to limit the movement of the mechanism for moving the shutter blades to onehalf of its full stroke to stop the blades and trigger movement when the blades are fully open, said mechanism for moving the blades closing the blades upon release of the trigger.

5. The bulb exposure shutter mechanism for camera shutters, defined in claim 4, characterized in that the stop interposed by said bulb exposure control being interposed directly in the path of the trigger for limiting the movement thereof.

6. The bulb exposure shutter mechanism for camera shutters defined in claim 4, characterized by the bulb control including a cam for engaging and moving a pin for operating the cover blinds in moving toward a bulb exposure indicating position, said spring for holding the cover blinds in an operative position covering the aperture returning said blinds to their operative position when the bulb control is moved away from its bulb indicating position.

CARL C. FUERST. 

